Worldwide tablet sales expected to reach 118.9 million units this year, led by Apple's iOS, a Gartner report reveals, adding that this number is a 98 percent increase from 2011's sales of 60 million units.

Carolina Milanesi, research vice president at Gartner, noted in the report Wednesday that Apple will continues to be the dominant media tablet operating system (OS), and is expected to account for 61.4 percent of worldwide media tablet sales to end users in 2012. This will be down from 66.6 percent in 2011.

Despite the arrival of Microsoft-based devices to the market, and the rollout of Amazon's Kindle Fire, Apple will continue to be the market leader through the forecast period, she added.

Even though PC vendors and phone manufacturers "want a piece of the pie" and have launched themselves in the media tablet market, there is very limited success outside of Apple with its iPad, Milanesi noted. She further explained that as vendors struggled to compete on price and differentiate enough on either the hardware or ecosystem, inventories had been built and only 60 million units reached the hands of consumers across the world.

This situation has not improved in early 2012, when the arrival of the new iPad had reset the benchmark for the product to beat, she remarked.

This is followed by the Android OS, which is forecasted to account for 31.9 percent of media tablet sales in 2012. The main issue with Android tablets is the lack of applications that are dedicated to tablets and take advantage of their capabilities, according to Gartner analysts.

Microsoft tablets are projected to account for 4.1 percent of media tablet sales this year, and grow to 11.8 percent of sales by end-2016.